Application Notes

From the measurement of AAVs to membrane proteins, nucleic acids and more, the applications of mass photometry are endless. Check out our library of application notes to learn more about label-free mass measurements for your biomolecule of choice. Upon submitting your contact details, you will be able to access our library of app notes and other mass photometry resources.

Basics of Mass Photometry


This technical note explains the basic concept of mass photometry single molecule detection and common errors that can influence mass photometry measurements. Considering the source of these errors while acquiring and analysing data will help extracting the best quality results.

Characterisation of protein interaction equilibria


Protein-protein interactions and protein complex formation are often multi-step reactions involving multiple species. Mass photometry, a novel analytical method, makes it possible to monitor complex equilibrium formation reactions, and to assess how changes in the chemical environment or protein concentration affect equilibria. Mass photometry directly measures the relative concentrations of all protein populations in a sample, in a single molecule fashion.

Mass Photometry of Adeno-Associated Viruses (AAVs)


Gene therapy is based on the delivery of genetic material to treat specific diseases. Adeno-associated viruses (AAVs) have been approved for use as gene delivery vehicles directly into target organs or tissues. One challenge of AAV-mediated gene therapy is quality control, due to the lack of techniques that can evaluate the relative abundance of AAVs that are loaded with their genetic cargo, are empty, or disassembled. Here we show how mass photometry can be used to control the integrity and purity of AAVs, and measure the cargo they carry.

Mass Photometry of Nucleic Acids


Mass photometry allows quantification of the mass distribution of biomolecules in solution. Its use in analysing the purity of proteins, characterising their oligomeric states, and quantifying their protein-protein interactions is established. However, the application of mass photometry to characterise other biomolecules is less well explored, including nucleic acids. Here we show how to use mass photometry to measure the mass, size and abundance of DNA, in the range of 100 to 5000 base pairs.

Mass Photometry on SARS-CoV-2


Mass photometry allows quantification of the mass distribution of biomolecules in solution. Its utility in analysing the oligomeric state and quantifying protein-protein interactions is here used to study the spike protein of the newly emergent SARS-CoV-2 virus and its interaction with the ACE2 receptor, thought to be the main entry route into human cells.

Optimizing and monitoring AAV capsid purification using mass photometry

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The SamuxMP mass photometer can quickly measure the empty/full capsid ratio during AAV downstream purification, making it ideal to use when optimizing and monitoring AAV purification processes. As the SamuxMP requires very little sample at low concentrations, it can be applied even from the earliest stages of process development – when sample amounts and concentrations are particularly limited.

Formation of PROTAC ternary complexes measured with mass photometry


This application note introduces a mass photometry-based assay, which can inform on the key aspects of the ternary complex formation. Mass photometry experiments do not require protein labelling or immobilisation and therefore allow direct visualisation and quantification of true molecule behaviour in solution.

Mass Photometry with Detergents


Detergents are widely used in biochemistry but display complex behaviour in aqueous solutions. Mass photometry is an effective tool for the study of biomolecules in detergent-containing solutions as well as for the evolution of molecular aggregation and micelle formation. In this application note, we describe how detergents affect mass photometry measurements and outline recommendations for how to optimise conditions for mass photometry experiments involving detergents. 

Mass Photometry in Denaturing Conditions


Mass photometry quantifies the mass distribution of biomolecules in solution. Its use in analysing biological samples for purity, integrity and function in native conditions has been established. However, its performance in denaturing conditions has not yet been thoroughly evaluated. In this application note, we demonstrate that mass photometry is a useful tool for studying the denaturation and renaturation of oligomeric proteins.

Mass Photometry of Nanocages


Ferritins naturally form nanocages to store and transport iron and are of interest in the fields of nanomedicine and drug delivery. The interior cavity of ferritins can be loaded with a variety of small molecules upon pH-induced disassembly and reassembly and the outer surface functionalised for targeting or soliciting a host response. Here we show how mass photometry can be used to quantify assembly, load, and homogeneity at single-particle resolution. Such measurements use little sample, are fast, label-free, and broadly applicable to natural and synthetic nanocages.

Quantifying heterogeneous AAV capsid loading using mass photometry

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Adeno-associated viruses (AAVs) are used in approved gene therapies to deliver genetic cargo to target cells. Distinguishing heterogeneously filled AAV capsids is an important aspect of sample characterization when developing these therapeutics. Here, data collected by Pharmaron Gene Therapy show that mass photometry can distinguish populations of AAV capsids with heterogeneous loading of genomic content and quantify the proportion of each population in a sample. 

Characterizing protein oligomerization with automated
mass photometry.

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Oligomerization can be critical for protein function, so to understand a protein’s function requires the ability to quantify its oligomerization state. Mass photometry can measure the mass distribution of a sample in native conditions and at a single-molecule level, with enough sensitivity to detect rare species. Automated mass photometry builds on these capabilities with easy and consistent sample dilution and manipulation, enabling thorough assays of oligomerization behavior.

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